Over a year ago, suddenly, USCIS began denying applications for renewals of Advance Parole (I-131) documents, if an applicant traveled internationally while waiting for the I-131 approval. It was followed by thousands of applications being denied for abandonment, people unable to return to the U.S. after a temporary trip abroad, refiling of thousands of advance parole applications, emergency I-131 filings at local USCIS offices, and resulted in strain of the USCIS resources.
Currently, the USCIS website indicates that if an individual has an approved advance parole document while a second one is pending, they can travel on the approved document, provided the advance parole document is valid for the entire duration of the trip (will not expire until after they had returned to the U.S.). In this case, the pending I-131 application will not be considered by the USCIS as abandoned.
See more here.